1. Field of the Invention
The present invention relates to a semiconductor device having a trench MOS barrier Schottky diode.
2. Description of the Related Art
Such a semiconductor device in the form of a trench MOS barrier Schottky diode is known from published German patent application document DE 10 2004 053 760 A1, and includes a semiconductor volume of a first conductivity type, the semiconductor volume having a first side which is covered with a metal layer, and including at least one trench which extends in the first side and is filled with doped polysilicon. In addition, on its wall the trench has at least one wall section which includes an oxide layer.
Schottky diodes usually include metal semiconductor contacts or silicide semiconductor contacts. In Schottky diodes, high-level injection does not take place in conducting mode, and therefore there is no clearing of the minority charge carriers upon shutoff. Schottky diodes switch comparatively rapidly and with little power loss. The term “high-level injection” refers to a state in which the density of the injected minority charge carriers comes into the range of the majority charge carriers.
However, Schottky diodes have relatively high leakage currents, in particular at higher temperatures, with a strong voltage dependency due to the so-called barrier lowering effect. In addition, for high reverse voltages, thick, low-doped semiconductor layers are generally necessary, which at high currents result in comparatively high conducting-state voltages. For this reason, power Schottky diodes in silicon technology, despite good switching behavior, are not suited or are only slightly suitable for voltages above approximately 100 V.